Accelerator of vulcanization



Patented Aug. 22,

ACCELERATOR oF momz n 1 Jan Teppema, ,Akron, Ohio, assignor to TheGoodyear Tire & Rubber Company, Akron,

' Ohio, a Corporation of Ohio No Drawing. Original application December1927, SerialNo: 239,2!56. Divided and this ap- I plication March 9,1929, Serial N 3"l5,898

1 17' Claims.

'My invention, which in abroad sense relates to the treatment of rubber,has particular relation to a method whereby the vulcanization of arubber compound may be hastened or accelerated. It has for one of itsobjects the provision of a new class of vulcanization accelerators forrubber compounds; for another, the pro vision of an acceleratorcomposition whichmay be manufactured inexpensively and which may bereadily incorporated into rubber upon the rolls of a mill without dangeror scorching A further object of the invention is to'provi'de avulcanization accelerator composed of the reaction product of an organicsulphide and a'2-halogen thiazole or substitution products of a2-halogen thiazole. my prior application Serial No. 239,266, filedDecember 10, 1927, for Accelerator of vulcanization which matured on May6, 1930, into aoUnited States'Letters Patent No. 1,757,930.

It has been observed heretoiore'that certain thiazole compounds, forbenzothiazole,

' o-sn s N when incorporated into a vulcanizable rubber compound,greatlyacceleratethe. rate of vul-v canization of the latter. Theresulting products have a high degree of tensile strength andelasticity. My invention is predicated upon the discovery that certainrelated thiazole compounds having the structural formula r iii-which Rrepresents ahalide, of which 2-chlor benzothiazole is an example, may becaused to for example; the sodium'salt of diethyl mama carbamate, toproduce materials having excellent accelerative properties. V

The first mentionedmaterial, as exemplified herein by 2-chlorbenzothiazole, may be convenientlyprepared bythc following method:

Dissolve" 200 parts of crude mercaptobenzothiazole in 400 partsofpentachlorethane and then bubble chlorine gasthrough this solution fora period of several hours while the solution This application is adivision of example, mercapto-' '7 react with alkali metal salts oforganic sulphides,

is being heated under a reflux condenser. Chlorination should continuepreferably from five to sevenhours, although this, period may beshortenedor increased somewhat at the will of theoperator. Howeverythelongerflperiods of chlorination result in a more complete reaction. Thereaction product is then distilled and the fraction boiling at atemperatureof from 240 C. to 252C. is separated from" the remainder andrepresents the major. portion or the reaction product of chlorine andmercaptobenzothiazole;

The 2-halogen benzothiazole prepared by the preceding method may becaused to reactwith various dithiocarbamates to produce excellentaccelerators forrubber compounds. The reaction product of Z-chlor.benzothiazole,andl'the' sodium salt of diethyldithiocarbamate is anexample of amaterial of this class which has been found to be-=veryefiicient. a

The following method may be employed inthe manufacture of this reactionproduct.

Dissolve l33 grams of; 2-chlor benzothiazole and 120' grams of sodiumdiethyl dithiocarbarnate in 500 cc.-of ethyl alcohol and refluxthesolution for a period of six hours. The alcohol is thendistilled offpreferably under reduced pressure and the reaction product, remaining inthe form of a' residual. oiljis washed with water, "The material maythen be dried with anhydrous ;calcium chloride (CaClz) and'filtered. Theoil when disj tilled at a pressure offive mm.'ofmercury yields a lightyellow oil which is a non-accelerator and a resinousresidue which is anaccelerator.

The invention is v.not limited to the reaction .product of Z-chlorbenz'othiazole with the alkali metal salts of dithiocarbamates, butitalso includes the substituted chlor-thiazoles; for example, 6-nitro2-chlor benzothiazole. The latter substance maybe caused to reactwithdiethyl g5 .dithiocarbamate bydissolving 35 grams of 6-nitro f2-chlor benzothiazole in alcohol, heating the solution' to boiling and.adding 30 grams of sodium fdiethyl dithiocarb'amate. After the solutionhas boiled for a period of from five toten' minutes it solidifies as ayellow mass. The vessel containingthe mass is exposed to the heat 'of asmall fiamefor a period of an'hour and is then cooled.

I The reaction product precipitates as a crystalline material whichshould be washed with water to remove any sodium chloride formed duringthe reaction. The crystalline material may be iurther'purified byrecrystallizing'it from boiling alcohol, from which. it precipitates inIorm of yellow needles havinga melting point of from p I20'to 122'degrees C.

The invention also includes the reaction products of 2-halogen thiazoleswith various dithiomate (a dark oily material), the reaction product ofsodium piperidyl dithiocarbamate with 2-chlor fi-nitrobenzothiazole (acrystalline substance having a melting point of 151'155 C.) and thereaction product of sodium dibenzyl dithiocarbamate with Z-chlor finitrobenzothiazole (a light yellow solid having a melting point of 141142 C.) v I All of these'materials :may be prepared by methods similarto those employed in the preparation of the reaction product of Z-chlorbenzothiazole and diethyl dithiocarbamate. The compounds-so prepared maybe employed as accelerators in most of the standard rubber compounds.The following is an example of a formula in which excellent results areobtained when any of the substances above mentioned are employed asaccelerators:

g Parts Extracted rubber. Zinc oxide 5 Sulphur 3 Stearic acid 1.5"Accelerator; .5

Rcaction product of 'z-chlor benzothiaeole and sodium diethyldithiocarbamate Load in at 700% elong.

Tensile strength 7 k gs/cm Percent Cure along.

r1 Reaction product of Z-chlor 6-nitrobeneothiaeole v and sodium diethyldithiocarbamate Load in kgs/em at Tensile Cure strength Efgg 500% 700%kgs/cm elong. along.

; represents a benzenoid group.

Reaction product of sodium dibeneyldithiocaflbamate and 2-chlorbcnzothiazole Reaction product of sodium piperidyl dithiocaw bamate andZ-chZor G-nitro beneothiazole Percent 500% elong.

7 elong.

elong.

500% elong.

elong. am

v c It will be apparent from the preceding tables that the use of theseaccelerators results in rapid cures at comparatively low temperatures,the vulcanized products'having excellent physical properties both withregard to tensile strength and 11C elongation. In the precedingexamples, specific reference has been made only to the reaction productsof 2-chlor benzothiazole with the sodium salts of the dithiocarbamates.In each case, the 2-brom benzothiazole may besubstituted for the. chlorthiazoles and the potassium or other salts of the dithiocarbamates maybe substituted in lieu of the sodium salt.

Although I have described in detail only thepreferred embodiments of theinvention, it will be apparent to those skilled in the art that it isnot so limited but that various minor modifications may be made thereinWithout departing from the spirit of the invention or from the scope ofthe .125 appended claims. It is intended that the patent shall cover, bysuitable expression in the appended claims, whatever features ofpatentable novelty reside in the invention.

What I claim is: I 1. A method of treating rubber which comprisesvulcanizing it in the presence of a material having the structuralformula in which R represents a piperidyl radical and R1 represents anaryl group. l e

2. A method of treating rubber which comprises vulcanizing it in thepresence of a material having the structural formula s s 'a-yi-s-o \R1 7v I in which R represents a piperidyl radical and 3. A method oftreating rubber which comprises vulcanizing it in the presence of thereappiperidyl dithiocarbamate. 4. A rubber product that has beenvulcanized in the presence of a material having the structural formulain which R is a piperidyl radical and R1 is ,a benzenoid group. n

5. A rubber product that in the presence of the reaction product ofsodium 1 piperidyl dithiocarbamate and a 2-halogen benzothiazole.

G. A method of treating rubber which comprises incorporating therein amaterial having the formula I R(J-SO R1 in which R represents apiperidyl radical and R1 represents a benzenoid group.

7. A rubber product that has been vulcanized in the presence of aZ-piperidyl carbamvl thiazyl sulphide. V

8. A method of treating rubber which comprises subjecting it tovulcanization in the presence of a material having the formula:

is I I:

' :9. A rubber product that has been vulcanized in the presence of amaterial having the formula j prises subjecting it to vulcanization inthe pres- 'ence of a material having the formula has been vulcanized.

stituted carbon atom.

11.A method of treating rubber which -comv prises vulcanizingit'in thepresence of a mate- -rial having the structural formula 1 R-(B-S-C m] vn v v N in which R representsa piperidyl radical and R1 represents anitro-substituted aryl group. 7 V 12. A method of treating rubber whichcomprises vulcanizing it in the presence of a material having thestructural formula V v V s s V nr -s-c RI N n in which R represents apiperidyl radical and R1 represents anitro-substituted benzene group.

13. Arubber product that has been vulcanized in the presence of amaterial having the struc-' v tural formula r v a I i s v -R(uJ-'-SO R,

in which R is a piperidyl radical and R1 is a nitro-substituted arylgroup.

14. A rubber product that has been vulcanized in the presence of amaterial having the structural formula s s 1 R-t -s0 m v n N in whichRis a piperidyl radical and R1 is a nitrosubstituted benzene group.

15. A method of treating rubberlwhich comprises incorporating thereinthe reaction product of sodium piper-idyl dithiocarbamate and a2-halogen. benzothiazole.

16. A method of treating rubber which comprises incorporating thereina2-piperidyl carbamyl thiazyl sulphide.

17. A method of treating rubber which comprises vulcanizing in thepresence of the reac-' tion product of a2-halogen nitro aryl thiazoleand a piperidyl dithiocarbamate;

JAN TEPPEMA.

